Pneumatic apparatus for driving connecting means, especially staples



June 15, 1965 H. E. B'ADE PNEUMATIC APPARATUS FOR mu VING CONNECTING MEANS ESPECIALLY STAPLES 2 Sheets-Sheet 1 Filed June 28, 1962 FIG-I INVENTOR. He: 0: 5. Ba de BY June 15,1965 I H. E. BADE PNEUMATIC APPA RATUS FOR DRIVING CONNECTING MEANS ESPECIALLY STAPLES 2 Sheets-Sheet 2 Filed June 28, 1962 3 4. r. L A 7 L5 B u. w 5 23 4 s s n z mw 7 "w 4 3 0 I I0 6 4' a m x. 4. m L 5 f 7 8 6 3 m l 9 5 0 M% 4 FIG-4 INVENTOR. Hgmz E. Bade United States Patent 3 Claims. 61. 91-399 The present invention relates to a compressed air operable apparatus for driving connecting means as for instance staples by means of a driver adapted to be actuated by a compressed air operable piston which is also returned to its starting position in a pneumatic manner.

It is an object of the present invention to provide a compressed air operable apparatus of the above mentioned type in which the return of the piston actuating the driver is effected by compressed air employed for operating the apparatus while the control of the return of the piston to its starting position will be so effected that the return of the piston will be assured in a proper and safe manner even if the driving strokes follow each other in rapid succession.

It is a further object of this invention to provide an apparatus as set forth in the preceding paragraph, in which the elements of the apparatus will be subjected to a minimum wear.

These and other objects and advantages of the invention will appear more clearly from the following specification in connection with the accompanying drawings, in which:

FIG. 1 illustrates a longitudinal section through an apparatus according to the invention with the driving piston in its retracted position.

FIG. 2 shows the front portion of FIG. 1 but with the driving piston occupying the end position of its driving stroke.

FIG. 3 is a section along the line III-III of FIG. 1.

FIG. 4 illustrates on a considerably larger scale than than that of FIGS. 1 and 2 the control valve mechanism shown in FIG. 1 for controlling the admission of actuating air to the driving piston of the stapler.

FIG. 5 illustrates the bottom portion of a slightly modified apparatus according to the present invention.

General arrangement According to the present invention, at the bottom of the cylinder in which the working piston reciprocates there is provided an insert which leaves free discharge passages for discharging the air ahead of the working piston while said insert is yielda-bly arranged in such a way that under the impact of the piston it will close the cylinder in an air-tight manner. As a result thereof, a closed working chamber will be created which makes it possible to permit compressed air admitted into the cylinder to become effective for the return stroke of the piston.

Inasmuch as with the apparatus according to the invention, the working piston during the driving stroke pushes the air ahead of the piston completely out of the cylinder, the piston can carry out its driving stroke at full power and unimpeded by an air cushion. Nevertheless the elastic bottom insert elastically absorbs the impact of the piston at the end of its driving stroke thereby cushioning the impact and protecting the apparatus. Inasmuch as the piston itself controls its return stroke, any special devices for this purpose will be superfluous.

The employment of the air effecting the driving stroke of the piston also for purposes of returning the piston to its retracted position assures a fast stroke and a suflicient holding force for the piston in cases where the cylinder 3,188,921 Patented June 15, 1965 head is provided with special means for this purpose as for instance a hollow cone for a corresponding protrusion of the piston.

As wear-resistant elastic material for the bottom insert, which also for permanent operation will assure a long life, synthetic materials and rubber materials of suitable degree of hardness as they are presently marketed may be employed.

Structural arrangement Referring now to the drawings in detail and FIGS. 1 to 3 thereof in particular, the stapler illustrated therein comprises a handle section 1, a main body 2 and a nose section 3. A portion of the means for feeding a succession of staples into the nose section 3 is generally designated 4. The staple feed means is conventional and does not form a part of this invention, and there are several satisfactory staple feed means available for this purpose.

The handle section 1 includes a large air chamber 5 and a conventional connection 6 for connection with a suitable supply of air under pressure, for instance air of 5 atmospheres above atmospheric pressure.

Fixed within the main body 2 is a sleeve forming a cylinder 7. The lower portion of sleeve 7 has a flange 8 resting through the intervention of a gasket 9 against the lower end face of the main body 2. The upper end of sleeve 7 is provided with a thread 10 which latter is engaged by a correspondingly threaded portion of a head 11 resting against the upper end of main body 2 through a gasket 12. Reciprocably mounted in sleeve 7 is a piston 13 having mounted therein the driver 14. The driver 14 is adapted to be guided in the nose section 3. The lower end of the cylinder 7 is closed by a bottom 87 which is threadedly connected to the cylinder 7 at 16. In bottom 87 there is provided an insert 86 which has a central longitudinal slot 19 forming a passage for the driver 14 and has a central bore 88 with a relatively narrow outlet opening 91. The bottom insert 36 preferably consists of an elastic synthetic material as for instance a polyurethane which excels in high wear resistance and on the other hand has a certain elastic compressibility.

The central portion of the cylinder sleeve 7 is surrounded by a chamber 24 in the main body 2 of the stapler. This chamber 24 is at one portion thereof broadened into a chamber section 25. The chamber 24 communicates with the interior of the cylinder 7 through a narrow bore 26 in the cylinder 7. Furthermore, from the chamber 24, 25 a passage 27 leads into the cylinder 7 through an outlet opening 28. This outlet opening 28 is located at such a level of the cylinder 7 as it corresponds to the location of the upper edge of the bottom insert 86 when the latter is in its normal position, i.e. is not under load.

*Interposed between the air chamber 5 and a passage 29 leading to the sleeve or cylinder 7 is a control valve generally designated 30 which is shown on a large scale in FIG. 4. As will be seen from FIG. 4, the lower portion of the handle section 1 is provided with a threaded bore 31 having threaded thereinto a bushing 32. This bushing 32 holds a cylindrical sleeve 33 in a bore 34 of the handle section 1 by means of a plate 35 and a plate 36 resting through the intervention of a gasket 37 against a surface 38. Reciprocably mounted in a bore 39 of bushing 32 is a pin 40 adapted to be actuated by a trigger 41. The trigger 41 is normally held in its FIG. 4 position by spring means (not shown in the drawings). Bore 39, in which the pin 40 is reciprocable, is provided with longitudinal grooves 42. The upper portion of pin 40 carries a sealing ring 43 by means of which normally, i.e. in FIG. 4 position of the pin 40, the grooves 42 are tightly sealed. When pin 40 is lifted, the said grooves 42 communicate with the interior of the cylindrical sleeve 33.

' opening 47 in the plate 35. The lower end of sleeve 46 is located opposite pin 49. Normally, i.e. in FIG. 4 posi-.

into the upper dot-dash position shown in FIG. 1. Thus,

the air in frontofthe pistonis permitted to escape,

tion of pin 4.0, the conical tip 48 of pin 43 is spaced from the lower end or sleeve'46, so that bore 49 of sleeve 46 communicates with the recess 50 inthe, bushing 32 However, this communicationbetween bore 49 and recess 50 can be interrupted when the trigger 41 is lifted soas to push a portion ofthe cone tip 48 into the bore 49.

Longitudinally displaceably mounted on sleeve 46 isa shank 51 carrying a'piston 52 whichis displacea-bly mounted in cylinder 34. Piston 52 carries a sealing ring 53. Similar to pin 40 also theprofiled shank 51'leaves free a passage 54 in plate '36.- At its upper end, shank 51 is provided with two sealing rings the upper one" 55 of which is adapted tightly to close an opening 56 comm-unicating with the chamber 5, whereas the lower ring 57 is adapted tightly to close the passage 54.: The upper por-' tion of the cylinderl33 has'a :reduced outer diameter so 7 pin 40 forms the servovalv-e forthe control valve.

When'the stapler is in readiness for carrying out a stapling operation, the control valve 30-occupiesthe through bore 88 and opening 91' into the atmosphere. At the end of the driving stroke" of piston 13, the latter impacts upon plate 92 and the bottom insert-86 and causes said plate 92 to close. the. gap" 93 and thereby'the interior of cylinder 7 in an air-tight manner withregard to the atmosphereQjAs soon as piston 13 during this driving stroke has passed by the opening or-bore'26, compressed air will'pass from compressed air'chamber 5 through passag-e 29 and the cylinder-portion above piston 13 through bore 26 into the chainbe'b24, 25. 1, vDue to the choking effect of the narrow opening 26 and in view of the increased yo urne owing't-o the bottomopcning 91, the compressed air undergoes a certain expansion. Through passage 27 and outlet opening or mouth 28',the air in chamber 24, passes below the piston 13 (see FIG. 2), inasmuch'as the lower piston edge of piston-13 due to the elasticspring back of thebottom insert 86, will after the termination of the impact freethemouth 28. Consequently, the corn pressed air passing through mouth, 28 below the lower pisthat this reduced diameter section together with the ho'using of the handle section 1 confines an annular chamber 58. This annular chamber 58 communicates with the ton surface acts upon piston13 and pushes the latter to its retracted position. The [above mentioned partial expansion of thecompressed air for the return'stroke of piston 13 i.e., the dimensionsof the opening 26 and the chamber-24,-25, are so selected that'pist-on 13 by means of its conical protr-ust-ion 68 will be held in the respective lining 69 of the cylinder head'11 to such an extentias it is deposition illustrated in FIG. 4.- -In this position, the cylinder chamber portion62 below the piston 52 communicates with the chamber 5 through bore 630i shankSl, through bore '49 of sleeve/t6, through recess 50, opening 64 and through opening 47 in plate 35. Consequently, the operating air pressure prevailing in the compressed air chamber 5 also prevails in'the cylinder portion 62 belowthe piston 52.

larger than the upper surface 66- of shank 51, the air pressure acting on the piston surface 65 firmly holds sealing ring. 55 in tight engagement with the surface 67 thereby preventing communication between the compressed air. chamber 5 and passage 29. v

If it is now desired to carry out a driving stroke with the driver,14,t-he trigger 41 is moved in the directionot.

sired. In other words, the holding force of the lining 69 in the cylinder head llas it is exerted upon the piston 13 will permit the desired increase in pressure prior to the actual starting of the driving stroke. That quantity of air which the piston 13 pushes-ahead of said piston during the return stroke passes through passage 29 and con- Inasmuch as the surface 65 of piston52 is the ar'rowA and immediately thereafterthe trigger is released again. In view of the lifting movement of trigger 41 in the direction of the arrow A, pin is lifted so. that its conical .tip 48 closes the bottom .end of bore'49 and no more air under pressure can pass from the compressed air chamber 5 through bore 49.; ,At the same time, the

lifiting movement of pin 40 also lifts oh? the sealing'ring 43 from its seat in bushing 32 so that theair from cylinder chamber section 62 can escape into the atmosphere through openings 47 and 64 and recess 50 and the grooves 42. The air under pressure now acting upon the upper shank end face 66 presses'the latter with its piston 52 downwardly into thev opening position'thereof in which ring 55 is lifted off from the surface 67 so thatnowcommunication exists between-the compressed air chamberS and the passage 29. while at the same time the sealing ring 57 closes the opening or passage 54 in plat'e 36. As aresult thereof, compressed'air now passes through passage" 29 and acts upon the piston area 1311 of the piston'13 so that the piston 13. moves downwardly.

88, 91 closed untilzthe pressure ,of the air pushed ahead Disc 92, aside from the narrow slot 90, maintains the discharge passage trol valve 30 into the exhaust. passage 61 and from there into the atmosphere. It will be appreciated in this connection thatafter the trigger 41 was released, the valve shank ,5'1 moved upwardly again into its FIG. 4 position due to the fact that compressed air could again pass from chamber 5 through bore 49 into recess 50 and from there through openings 64 and 47 into the cylinder chamber portion 62 below the piston 52iand thereby move the latt-er together withthe shank 51'into the position where the sealing ring'55'closes the opening 56.v The, quantity of air which the piston 52 during its upward movement with regard to FIG. 4'pushes ahead thereof escapes through the exhaust: passage 6-1. Similarly, the air Whichthe working piston 13 during its upward stroke has pushed into the passage 29. passes from the latterv through the opening 54 into the cylinder cham-ber 59 and from there through the openings 60 into the exhaust passage 61, the openings 60 acting in'a sound mufiling manner.

Also with the modification illustrated in FIG; 5 the elastiobottom insert comprises a bottom section 86 inserted in'the cylinder bottom 87 and having a relatively wide bore SS'communicating with the atmosphere torn insert-furthermore comprises an upper section in form of a flat disc 89 which loosely lies on the bottom section 86 and has a smalllongitudinal air passage-90 at both sides of the driver 14. The design of thecylinder end substantially corresponds to that shown in FIG. 1. During the driving stroke, the driving piston of the apparatus pushes the air in-front thereof athigh speed through slotor air passage 90 into the bore 88; The

thus created strong turbulence, which is additionally favoredby the relatively narrow exit 911, will in conformity with the continuity equation by Bernouli, bring of the piston during the driving stroke of the latter has I increased to such an extent that it bends disc 92 into a dot-dash calotte shape, while its central portion extends into the bore 88. Thus, the marginal portions of disc 92 will be bent upwardly and lifted off from the upper end a 7 face of the insert section 86. The air now enters the thus about'a lifting off of disc 89 from the lower insert section 86and, due to the thus forminggap,enable the air to throw the 'disc 89 upwardly, which latter thus permits the air in front of the piston to escapeth'roughbore 88 and opening 91 into the atmosphere. At the end of the driving stroke of the piston, the latter impacts upon disc 89 and presses the same against the insert section 86.

The return stroke of the piston is effected in a manner similar to that described in connection with FIG. 2 inasrriuch as the air under pressure will pass through bore 26, through chamber 24, 25 and mouth 28 below the piston. In view of the automatic control of the return air for returning the piston, an additional resilient mem ber becomes superfluous; I

It is, of course, to be uflderstood that the present invention is, by no means, limited to the particular constructions shown in the drawings, but also comprises any modifications within the scope of the appended claims.

What I claim is:

1. In a pneumatic driving apparatus, especially for staples, a cylinder, a double acting piston reciprocable in said cylinder from a first position representing the start of a driving stroke to a second position representing the end of a driving stroke, and vice versa, said piston having a first area actuatable by air under pressure for moving said piston from said first position to said sec end position, said piston also having a second area arranged opposite said first area and actuatable by air under pressure for moving said piston from said second position to said first position, a driver connected to said piston for movement therewith and for driving a connecting element into a work piece, first passage means leading into one end portion of said cylinder for conveying air under pressure to said first piston area to effect a driving stroke of said piston, abutment means arranged in the other end portion of said cylinder for resiliently stopping said piston at said second position, said abutment means comprising a first member with a bore therethrough and an outlet opening communicating with the atmosphere, said outlet opening having a diameter relatively small with regard to the diameter of said lastmentioned bore, said abutment means also comprising a second member in the form of a plate adapted to rest on said first member and also to be lifted off said first member in response to the air pressure in the bore of said first member exceeding the air pressure prevailing between said piston and said plate, said second member having a passage permitting the movement of said driver therethrough and additionally permitting air between said piston and said plate to escape through said bore and said outlet opening into the atmosphere, said piston being adapted to close said last mentioned passage in response to said piston impacting upon said plate, and second passage means controlled by said piston during its driving stroke for conveying air under pressure to said second piston area when said second piston is in its second position to thereby return said piston to its first position.

2. A pneumatic driving apparatus according to claim 1, in which said plate forms a thin disc elastically deformable into a calotte by the pressure of the air pushed ahead of said piston during movement of said piston from its first position to its second position.

3. A pneumatic driving apparatus, especially for staples, having a cylinder with a double-acting air operable piston reciprocable in said cylinder and carrying a driver and with resilient yieldable abutment means for abutment with said piston at the end of its driving stroke, in which said abutment means comprises a first member having a relatively wide bore and a relatively narrow outlet opening establishing communication between that end portion of said bore which is remote from said piston and the atmosphere, said abutment means also comprising a second member in the form of a flexible plate adapted to rest on said first member and to cover up the other end portion of said bore With regard to said cylinder, said plate having a passage permitting the movement of said driver therethrough and additionally permitting a restricted air flow from between said piston and said plate into said bore and through said outlet opening into the atmosphere, said plate being adapted to be lifted oil said first member in response to the air pressure acting on that side of said plate which faces toward said first member exceeding the air pressure acting on that side of said plate which faces toward said piston.

References Cited by the Examiner UNITED STATES PATENTS 1,494,030 5/24 Slater 91-399 2,985,139 5/61 Powers et al. 9l4l6 3,040,709 6/62 Wandel 91-4l6 FRED E. ENGELTHALER, Primary Examiner. SAMUEL LEVINE, Examiner. 

1. IN A PNEUMATIC DRIVING APPARATUS, ESPECIALLY FOR STAPLES, A CYLINDER, A DOUBLE ACTING PISTON RECIPROCABLE IN SAID CYLINDER FROM A FIRST POSITION REPRESENTING THE START OF A DRIVING STROKE TO A SECOND POSITION REPRESENTING THE END OF A DRIVING STROKE, AND VICE VERSA, AND PISTON HAVIN A FIRST AREA ACTUATABLY BY AIR UNDER PRESSURE FOR MOVING SAID PISTON FROM SAID FIRST POSITION TO SAID SECOND POSITION, SAID PISTON ALSO HAVING A SECOND AREA ARRANGED OPPOSITE SAID FIRST AREA AND ACTUATABLE BY AIR UNDER PRESSURE FOR MOVING SAID PISTON FROM SAID SECOND POSITION TO SAID FIRST POSITION, A DRIVER CONNECTED TO SAID PISTON FOR MOVEMENT THEREWITH AND FOR DRIVING A CONNECTING ELEMENT TO INTO A WORK PIECE, FIRST PASSAGE MEANS LEADING INTO ONE END PORTION OF SAID CYLINDER FOR CONVEYING AIR UNDER PRESSURE TO FIRST PISTON AREA TO EFFECT A DRIVING STROKE OF SAID PISTON, ABUTMENT MEANS ARRANGED IN THE OTHER END PORTION OF SAID CYLINDER FOR RESILIENTLY STOPPING SAID PISTON AT SAID SECOND POSITION, SAID ABUTMENT MEANS COMPRISING A FIRST MEMBER WITH A BORE THERETHROUGH AND AN OUTLET OPENING COMMUNICATING WITH THE ATMOSPHERE, SAID OUTLET OPENING HAVING A DIAMETER RELATIVELY SMALL WITH REGARD TO THE DIAMETER OF SAID LASTMENTIONED BORE, SAID ABUTMENT MEANS ALSO COMPRISING A SECOND MEMBER IN THE FORM OF A PLATE ADAPTED TO REST ON SAID FIRST MEMBER AND ALSO TO BE LIFTED OFF SAID FIRST MEMBER IN RESPONSE TO THE AIR PRESSURE IN THE BORE OF SAID FIRST MEMBER EXCEEDING THE AIR PRESSURE PREVAILING BETWEEN SAID PISTON AND SAID PLATE, SAID SECOND MEMBER HAVING A PASSAGE PERMITTING THE MOVEMENT OF SAID DRIVER THERETHROUGH AND ADDITIONALLY PERMITTING AIR BETWEEN SAID PISTON AND SAID PLATE TO ESCAPE THROUGH SAID BORE AND SAID OUTLET OPENING INTO THE ATMOSPHERE, SAID PISTON BEING ADAPTED TO CLOSE SAID LAST MENTIONED PASSAGES IN RESPONSE TO SAID PISTON IMPACTING UPON SAID PLATE, AND SECOND PASSAGE MEANS CONTROLLED BY SAID PISTON DURING ITS DRIVING STROKE FOR CONVEYING AIR UNDER PRESSURE TO SAID SECOND PISTON AREA WHEN SAID SECOND PISTON IS IN ITS SECOND POSITION TO THEREBY RETURN SAID PISTON TO ITS FIRST POSITION. 